To explore the effect of dietary thyme on muscle concentrations of inosine acid and inosine in Tan Sheep,the total mixed diets added thyme by 5%( thymus low group) and 10%( thyme high group),and the control group( without thyme) were fed to sheep and the muscle samples were measured by HPLC. The result showed that thyme could improve the contents of inosine acid which related with the the amount of added thyme. A 5% of thyme added into the total mixed diets could greatly improve the content of inosine acid( P0. 01),and delayed the inosine acid degradation generates inosine within a certain time,and enhance IMP /( IMP + I) freshness value of muscle,and improve the content of flavor substances and the flavor of Tan sheep muscles. However,10% of thyme had little effects on muscle levels of inosine acid and inosine and tended to be a slight downward.